A 16-year-old boy is in custody after a 16-year-old girl was stabbed to death today at a high school in Milford, Connecticut.

Police are investigating whether the victim, Maren Sanchez, was stabbed because she declined an invitation to the junior prom. 

Her cousin, Edward Kovac, spoke at a news conference.

"After a terrible experience like this, we can never forget the lessons about school violence that must be learned from this tragedy," he said.

School staff and paramedics performed live-saving measures on the girl, but she later died at a hospital. The prom set for this evening has been postponed.